Controlled Preparation of Uniform TiO₂-Catalyzed Silver Nanoparticle Films for Surface-Enhanced Raman Scattering

Abstract

Silver nanoparticle (AgNP) film is a kind of useful material in biochemical and biomedical fields as it can be used as a sensor based on its surface plasmon resonance for surface enhanced Raman scattering (SERS) analysis. In this work, a uniform AgNP film with controlled nanoparticle size, shape, and density have been prepared on TiO 2 film in a AgNO 3 solution by photocatalysis reduction method. The influences of TiO 2 film thickness and morphology on the AgNP's growth have been systemically studied. It is found that a thicker TiO 2 film with nanocrystalline morphology leads to a higher AgNP's growth rate, while a thinner TiO 2 film with membrane morphology leads to a lower AgNP's growth rate. Experimental SERS results show that the AgNP film prepared with different TiO 2 films and ultraviolet light irradiation time exhibit different SERS signals of rhodamine 6G (10 −6 M). Atomic force microscope and scanning electron microscope analysis reveal that the size effect is a key factor affecting the SERS of our prepared AgNP films, which has also been evaluated by finitedifference time-domain simulation. It is found that the larger the average AgNP's size (≤λ/4) and roughness, the higher the Raman enhancement. The SERS mapping images exhibit a good uniform Raman enhanced results in our prepared TiO 2catalyzed AgNP film with a low relative standard deviation of approximately 10%.

Hierarchical Ag/TiO2/Si Forest-Like Nano/Micro-Architectures as Antireflective, Plasmonic Photocatalytic, and Self-Cleaning Coatings

“…Recently, several researchers have developed multifunctional (i.e., self-cleaning and antireflective) coatings by double-layered TiO 2 -SiO 2 nanostructured films, layer by layer assembly of TiO 2 nanoparticles and SiO 2 submicrometer particles as building blocks, and by synthesizing the raspberry-like SiO 2 -TiO 2 core–shell nanoparticles, etc. − Also, the nanostructured TiO 2 (e.g., nanopores, nanorods, and hierarchical architectures) has been studied as a multifunctional coating since it offers a large effective surface area, which can reduce the surface reflectance losses and enhance the possibility of collecting the incident light for photocatalytic reaction. ,− To further improve the photocatalytic activity of TiO 2 , metal nanoparticles have been used for plasmonics. Metal nanoparticles can be easily synthesized and coated on the surface of various substrates by a simple and cost-effective dip-coating method. − Furthermore, for the highly roughened TiO 2 , the superhydrophilic surface might help the metal nanoparticles in aqueous solution to relatively well form the surface due to its strong affinity to water . To the best of our knowledge, there is no fabrication and characterization of metal nanoparticle-integrated TiO 2 /Si with forest-like hierarchical nanorods/micropyramid arrays for antireflective and self-cleaning (i.e., plasmonic photocatalysis and superhydrophilicity) coatings via a facile, cost-effective, and low-temperature CBD technique.…”

Photocatalytic growth and plasmonic properties of Ag nanoparticles on TiO2 films

“…Using TiO 2 films as the photocatalytic reduction media, the Ag 1 ions in the AgNO 3 solution are reduced on TiO 2 films under UV irradiation, forming TiO 2 -catalyzed Ag NP films, which have been used as the substrates for surface enhanced Raman scattering (SERS). 10,11 However, the growth dynamics of Ag NPs still remains an open question and has attracted fundamental interest. Ag NPs synthesized by photocatalytic reduction generally exhibit irregular spherelike shapes.…”

Charge Transfer Tuned by the Surrounding Dielectrics in TiO2-Ag Composite Arrays

“…Of these peaks, the peaks at 1077, 1188, and 1474 cm −1 were assigned to the ν(C-S), δ(C-H), and ν(C-C) stretching vibration, respectively, which were dominated by characteristic a1 vibrational modes [23,24,25]. The δ(C-H) at 1141 cm −1 , [ν(C-C) + δ(C-H)] at 1391 and 1436 cm −1 , and ν(C-C) at 1577 cm −1 were interpreted as b2 modes, as shown in Table 1 [26,27,28]. For pure Ag, the enhanced peaks were believed to be due to the roughness of the nanocap caused by Ag nanoparticles.…”